Cosmetics units, and in particular mascaras, consist of a storage container in which a supply of the viscous or almost paste-like cosmetic to be applied is located. This storage container can be sealed with a cap. Most frequently, the cap itself forms a part of the applicator. For this purpose, a slim elongate shaft is generally attached to it, on whose end facing away from the cap (i.e. distal end) a brush is mounted which serves for applying the cosmetic. The brush, shaft and cap together thus form the applicator.
Whenever the cap is placed on the storage container and seals it, the shaft protrudes deeply into the storage container and dips the brush into the supply of cosmetic, whereby the shaft and the brush are being wetted.
When the applicator system is withdrawn, at least the shaft, but generally also the brush, have to be freed from excess cosmetic. This is the only way to prevent the excess cosmetic from dripping off inadvertently and causing stains during use.
For this purpose, a wiper is attached in the area of the opening of the storage container through which the shaft and, in the end, also the brush attached thereto, are pulled out from the storage container.
Such wipers have long been known in many various forms.
A typical wiper is configured as a more or less conical “sleeve” from a rather resilient material, whose smallest sleeve cross-section is slightly smaller than cross-section of the shaft carrying the brush. Thus, the smallest sleeve cross-section rests against the shaft with a certain bias and therefore wipes off a large part of the cosmetic adhering to the shaft when the shaft is withdrawn.
If no special corrective measures are taken, it can hardly be avoided that a negative pressure is created in the storage container by the wiper during the withdrawal of the shaft, because no or not enough air is able to flow into the storage container from the outside which could occupy the space that the part of the cosmetics applicator which has been withdrawn in the interim had previously occupied. In any case, the negative pressure thus created in the storage container abruptly collapses right at the moment when the applicator is about to leave the wiper behind completely. The pressure surge thus created can lead to undesired squirting in the case of a quick withdrawal. Even where this is not the case, it can be observed, in any case, that a bothersome excess of the cosmetic thus collects at the outermost distal end of the brush.
Conversely, an overpressure builds up in the storage container during every relatively quick reinsertion of the mascara brush, because the air displaced by the mascara brush cannot escape quickly enough to the outside along the gap largely provided by the wiper. A certain amount of mascara mass thus tends to be pushed past the wiper into the wiper antechamber (so-called backwiping). The deposits that are thus created in a rather significant extent over time are bothersome.
The above-mentioned effects are particularly pronounced if the user, prior to the actual application of the mascara, withdraws the mascara brush several times to a certain extent and reinserts it, in order to achieve a wetting of the mascara brush that she feels is optimal.
In order to correct this problem, it has been proposed that at least one gap be provided in the actual sealing lip of the wiper, the gap being dimensioned in such a way that the wiper does not seal nearly hermetically anymore, but that air can flow into the storage container. In this case, it is problematic that, only by appropriately dimensioning the free cross-section of the gap, it can be ensured that the at least one gap is not temporarily sealed anyway by the cosmetic building up before the wiper during the withdrawal, thus temporarily affecting the gap's intended function. Such a large gap, however, jeopardizes the sealing function of the wiper, which is not only supposed to wipe, but also to prevent that the cosmetic mass runs into an area behind the wiper from which it cannot be removed anymore by the wiper when the applicator is withdrawn.
In order to solve the problem, it is alternatively proposed in the prior art that a single or a few pressure relief opening(s), which, however, are spaced far from one another, are installed laterally in the area close behind the contact surface of the sealing lip, so that a “bypass” for the air flow is provided, as it were.
However, this approach also involves a trade-off.
Because in the case of one or a few widely spaced pressure relief opening(s) with an only small opening cross-section, there is the danger that every one of these pressure relief openings clogs up relatively quickly with cosmetic, which was inadvertently deposited therein and then dried—this is due to the fact that purely static conditions substantially prevail in the case of a pressure relief opening located in the bypass, which is why such a pressure relief opening is subject to virtually no self-cleaning effect, in contrast to a pressure relief opening directly located in the actual sealing lip, which is exposed to a permanent interplay of forces.
However, in the case of one or a few pressure relief openings with a relatively large cross-section, the problem quickly arises that, at least in the case of unfavorable storage of the cosmetics unit (e.g. in a ladies' handbag in an “upside-down position”), they will nevertheless let cosmetic mass come into the area behind the wiper over time.
Moreover, it is a fact that none of the wipers known so far provides the option that the user can actively reduce a load on the brush serving for the application that is partially or intermittently perceived as being too large, without again having to push the brush through the wiper into the storage container and withdraw it through the wiper again.
In view of this, it is the object of the invention to provide a wiper which reliably prevents a negative pressure or overpressure from building up during the applicator's withdrawal from or insertion into the storage container, without involving the risk that a larger amount of the cosmetic comes into the area behind the wiper, and/or to provide a wiper that enables a specific reduction of the load, as is described above.